In lighting applications dedicated to switching on and off lights in a room a lack of sensitivity of presence detection systems comprising passive infrared sensors leads to a false switching off of the lights. This is highly irritating for a person present in the room. For example the lights can be switched off if the person is still sitting and just typing, i.e. making only some minor movements. The well known “waving” is then needed to switch the lights on again. This problem is resolved in the art by using presence detection systems that use a sensor of a high sensitivity in order to detect also the small movements of the person. For example ultrasound sensors in combination with passive infrared sensors can be used. Such systems are for example able to detect the person who is sitting behind a personal computer. Thus the person is not making any major movements, only minor movements. Using such highly sensitive sensors delivers another disadvantage. In particular, because of the high sensitivity of the sensor, the sensor sometimes concludes the person's maintained presence while no person is present in the room. For example, a plant's leaf movement can cause a false conclusion of presence of the person in the room and consequently the lights will remain on. Moreover, using two sensors, the ultrasound sensor in combination with passive infrared sensor, is relatively expensive.